The broad long-term objective of this application is to become a Transplant Study Unit (TSU) in proposed Cooperative Clinical Trial in Transplantation (CCTT). The major purpose of the CCTT is to evaluate the safety and efficacy of new immunotherapeutic agents in the prevention and treatment of kidney graft rejection by a controlled multicenter clinical trial. The specific aim of this TSU is to conduct a prospective, randomized, double-blind clinical trial to compare the safety and efficacy of FK506 with Cyclosporin in a sequential immunosuppressive regimen, including Minnesota Antilymphocyte Globulin (MAG), Prednisone, and Azathioprine. While the primary outcome variable is graft loss, as defined by death, dialysis dependency or transplant nephrectomy, important secondary outcome variables are the frequency and severity of rejection episodes, infections, hypertension, drug toxicities, lipid profiles, glucose intolerance, neoplasms and days of hospitalization. Patients will be stratified by donor source and transplant number. Observations regarding the outcome variables are collected by blinded observers in duplicate fashion, and entered into a specially designed, electronically-integrated transplant data base (UPSTART), featuring Sybase language, Microvax II capacity, and on-line statistical analysis. By sample size estimates, this TSU has a sufficient number of patients of appropriate race and gender to reach statistically valid conclusions about the comparisons proposed between FK506 and Cyclosporin. This TSU has appropriate clinical, scientific and technical expertise in kidney transplantation, immunosuppression, and transplant immunology to conduct the proposed trial, and to participate in the development of a consensus protocol by the CCTT Steering Committee to evaluate immunotherapeutic agents, both singly and in combination.